Drive chain questions

Anonymous
Anonymous Posts: 79,666
edited March 2015 in Workshop
Sorry if this has been asked a million times but I have a few questions,

Currently running 8 speed on my bike.

1) I need a new chain, it's stretched, do I really need to change my cassette as well, or is this just a sales thing?

2) how's best to measure the new chain if the old one is stretched?

3) If I wanted to upgrade to 9 or 10 speed, is all I need to change is the shifter, the chain, and the cassette, or do I need a new rear dérailleur as well?

Comments

  • trailflow
    trailflow Posts: 1,311
    edited March 2015
    Firstly how do you know your chain is stretched ? If there are no problems currently, have you thought about running both chain and cassette into the ground ? Thats what i would do,instead of replacing periodically. 8 speed chains and cassettes can be bought fairly cheaply nowadays.

    1. Depends how much mileage you have done. The only way to know is to try. If it skips and jumps. you need a new cassette. If it still skips after that then your chainrings might be worn, but they take a lot longer to wear and need replacing less frequently.

    2. It wont have stretched that much. Just take the old one off and lay them side by side to get the right length or count the links.
  • dgunthor
    dgunthor Posts: 644
    3. just need the rear 10 speed shifter. rear and front mech should work fine. new chain and cassette obviously
  • keef66
    keef66 Posts: 13,123
    As above, just fit a new chain and see how it goes. Stick it in the middle of the cassette and try a few hill starts. If you find the chain jumping forward on the sprockets and bringing your testicles into sudden contact with the top tube, you should then try a new cassette.

    For chain length I never assume the old one was correctly sized. For a double I route it round the biggest chainring and biggest sprocket but not through the rear mech, then add a link. For a triple it's biggest chainring / smallest sprocket, through the rear mech and adjust length so the jockey wheels are vertically aligned.

    Yep, to go to 10 speed the shifter(s), chain and cassette is the minimum you need to change.

    FWIW I find 8 and 9 speed transmissions a lot more durable than 10 speed stuff, so if you're commuting on a budget, bear that in mind.

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